when appending to a directory, the copy of the offset in the dent was
set to the offset that the write was supposed to happen at -- however,
for DMAPPEND files the offset is always at the end of the file. Until
the file was closed, stat would show the wrong directory info.
Implement a hangup ctl command that flushes the
queues, but keeps the filter around.
This can be usefull for low-overhead traffic blocking,
as only the file-descriptor needs to be kept around
and the queues can be flushed.
No user-space process is needed to consume packets
and no buffers are wasted.
example:
aux/dial -e -o hangup 'ipmux!ver=4;src=8.8.8.8' rc -c 'echo 0 > /srv/blocked'
rm /srv/blocked
It seems some protocols are unprepared to
deal with ipoput*() raising an error
(thrown from ifc->m->bwrite()).
so catch it and return -1 (no route) instead.
We were accidentally searching the key for '&', instead of the value.
Inferno received this exact fix at some point, but it never made it back to Plan 9.
the installed version of git has a bug; removing
this file will trigger some spurious removals of
test files, so hold off deleting it until people
have time to install a fixed git
directories need to sort as though they end with a '/',
when running through them for comparison, otherwise we
flag files as added and removed spuriously, leading to
them incorrectly getting deleted when merging commits.
Instead of Proc { Mach *mp; Mach *wired; },
track affinity by an integer representing
the mach number instead.
This simplifies the code as it avoids needing
to compare with MACHP(m->machno).
Wiering a process to a processor is now done
by just assigning affinity and then set a flag
that it should not change.
Call procpriority() when we want to change
priority of a process instead of managing
the fields directly.
The idea is:
When we call sched() with interrupts disabled,
it must not return with them re-enabled.
The code becomes easier to reason about if
we make sched() preserve interrupt status,
which lets us call sched() from an interrupt
handler (with interrupts disabled) without
risking preemption by another interrupt once
sched() returns which can pump-up the stack.
This allows removing Proc.preempted flag as
it is now impossible for interrupts to
preempt each other in preempted().
Extra cleanups:
make interrupted() _Noreturn void
and remove unused Proc.yield flag.
the symptom is that ping is apparently skipping
transmits which recover with the next send,
resulting in exactly send-period spikes in
the ping rtt.
It appears that the core seems to reorder writes
to uncached memory, which can result in the doorbell
being written before the descriptor status bits
are written.
put a coherence() barrier before writing doorbell
fixes it.
thanks sigrid for reporting the issue!
On a multiprocessor, the scheduler can run into
a very unfair distribution of processes to cpus
when there are more long-running processes than cpus.
Say we have a 4 cpu machine and we run 4 long-running
proesses, each cpu will pick up a single process
and each process will get 100% of its fair share.
Everything is good so far.
If we start more long-running processes, all these
processes are going to be picked up by the cpu core
that runs most sporanic / bursty work loads as it
is calling sched() more often.
This results in all the extra long-running prcoesses
to cluster around the same core resulting in very
unfair sharing of load.
The problem is that once a process runs on a cpu,
it stays on that cpu as processor affinity
is never reset.
Process migration only happens when a cpu cannot
find any process to run, given the affinity
constrains, but this can never happen when
the system is under full load and each cpu
always has a low-priority long running
process to run.
How do we fix this?
The idea of this hack is to reset processor
affinity in ready() when its priority changes or,
when it appears to be a long-running process.
That way, we give every cpu a chance to pick
it up and share the load.
This is not a ideal solution of course. Long term,
we should probably have separate runqueues per cpu
and do the balancing explicitely.
In the sched() function, the call to reprioritize()
must be done before we set up, as reprioritize()
calls updatecpu(), which determines if the process
was running or not based on p == up. So move
the call to runproc() itself.
while rehashing the same files over and over will work
just fine, it can be slow with a large number of large
files; this makes 'git/comit .' perform much better in
repos with a large number of large binary blobs.
compress when the log doubles in size, rather than
using a fixed size heuristic; this means that we
don't start compressing frequently as the log gets
big and the file system gets fragmented.
this happens in libframe:
/sys/src/libframe/frutil.c:80: x -= (x-f->r.min.x)%f->maxtab;
but there's no way to control when the user changes the
maxtab value, so it's samterm's responsibility to
sanitize it.
we were copying the owner and group of the parent dir into the fid
on create, but we forgot the mode; fix that, so that we don't check
perms against the wrong dir.
